Because time is too abstract to imagine we use space as a proxy. Past is behind, future is in front. We think of moving left to right along a timeline (if you're an English speaker).
Far away lacks detail — that can be true of space or time. Up close is more vivid — also true of space and time.
We use what we see in the present to fill in our memories of the past and as primary material for imagining the future.
Imagination - “see” the future
Memory - “see” the past
Perception - “see” present (most reliable but still not that reliable)
Keywords & Nodes